In connection with accidents involving for example tank cars, gas tanks, cisterns, pipelines, production lines and the like it is often necessary to evacuate their contents before normal safety measures can be initiated. The work involved in the evacuation of inflammable, explosive or other hazardous and perilous gases and liquids constitutes a considerable hazards both to persons actively taking part in the rescue work and to persons present in the immediate surroundings.
Rescue methods according to prior-art technology therefore often involve vacating people from the immediate surroundings, which could be quite an extensive operation in case the accident occurs for example in a densely populated area.
According to prior-art methods of evacuating gases and liquids from containers the valves of which have become unserviceable or for some other reason cannot be used, a sleeve is welded onto the container wall so as to be tightly secured thereto. A valve is then mounted on the sleeve and an aperture is drilled through the valve and the container wall with the aid of a special drill. The reason for attaching the sleeve by means of welding is to ensure that it can withstand the forces exerted in the drilling operation. The sleeve, the valve, and the cover surrounding the drill usually are filled with nitrogen in order to reduce the risk of ignition by the heat generated in the drilling operation. Hoses are connected to the valve, causing the contents to flow automatically or by suction into a fresh container, alternatively to a flare for flaring. Today, the welding step as well as the subsequent drilling step are at least partly effected manually, which often constitutes a danger to the lives of the persons involved, particularly if the containers hold explosive, poisonous or inflammable materials and both steps are carried out under heat-release conditions.
Naturally, it is a serious problem that several steps of the evacuation work according to prior-art technology need to be carried out in a manner endangering the lives of the workmen and therefore also constituting a considerable risk of exposing the surrounding area to hazards. Consequently, there is a considerable need for a method allowing containers holding dangerous material to be emptied in a less risky way, particularly in conjunction with clearance work occasioned by accidents or the like. Since dangerous goods is transported also through densely populated areas, there is likewise a need for avoiding, as far as possible, situations that may lead to a large number of individuals having to be vacated from the immediately surrounding area. This type of operations delay the rescue work proper and are both expensive and complex.